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Health burden of gastrointestinal symptoms resulting from swimming in fecally-contaminated recreational waters.
Citation:
Wade, Tim, A. Dufour, AND E. Sams. Health burden of gastrointestinal symptoms resulting from swimming in fecally-contaminated recreational waters. Presented at Water and Health Conference, October 29 - November 02, 2012.
Impact/Purpose:
Assess health burden of gastrointestinal symptoms resulting from swimming in fecally-contaminated recreational waters.
Description:
Millions of people swim and recreate in oceans and lakes every year. Fecal contamination of these waters can occur from sewage discharges, runoff, and other point and non-point sources. Measures of fecal indicator contamination (e.g., the fecal indicator bacteria E. coli and Enterococci) have been linked to illnesses, notably gastrointestinal (GI) illness, among swimmers. The National Environmental and Epidemiologic Assessment of Recreational Water Study (NEEAR) was conducted at four freshwater and three marine sites in the United States and over 25,000 beachgoers were enrolled. Beach sites were located near treated sewage discharges. Each day up to 18 water samples were collected and tested for the fecal indicator bacteria Enterococcus using culture methods and quantitative polymerase chain reaction (qPCR). Ten to twelve days after the beach visit, subjects answered questions about health symptoms, including diarrhea, nausea, vomiting and stomach cramps experienced since the beach visit. Economic and physical burdens were also obtained, such as days lost from school, work and other activities, the use of medications and visits to health care facilities. Subjects were categorized into four exposure groups based on geometric means of Enterococcus qPCR calibrator cell equivalents (CCE): unexposed (non-swimmer); under 200; 200-475; and over 475 CCE. Logistic regression models with a random intercept for beach site were used to estimate the risk of swimming in poor water quality (over 475 CCE). Model results were used to calculate risk differences or excess risk per 1000 swimmers. Slightly over 6% of non-swimmers reported GI illness compared to over 11% of swimmers exposed to Enterococcus over 475 CCE. Adjusted odds ratios for GI illness compared to non-swimmers were: 1.26 (p<0.0005), 1.48 (p<0.0005), and 1.65 (p<0.0005) for under 200, 200-475 and over 475 CCE exposures, respectively. Among those reporting GI illness, 41% reported interference with the